The PNG specification includes physical pixel dimensions (see here). Does Fabric.js support setting these values? If so, how can these be set?
Edit: I should mention that I am trying to do this entirely in the browser. I'm not using NodeJS.
fabricJS does not support DPI values on output, but lucky enough i wrote a small library that will let you do that!
It works on blob and dataurl:
https://www.npmjs.com/package/changedpi
I know seems pure advertising but i think this piece of code will do that and it does just that, it works for both PNG and JPEG.
// create the dataUrl at standard 72dpi
var dataUrl = canvas.toDataURL('image/jpeg', 0.92);
var daurl150dpi = changeDpiDataUrl(dataUrl, 150);
or
// create the blob at standard 72dpi
canvas.toBlob(function(blob) {
changeDpiBlob(blob, 300).then(function(blob){
// use your changed blob
})
},'image/jpeg', 0.92);
The method it uses here are not the one from fabricJS, for the dataUrl there is no problem since you can generate a dataurl and pass it to this function here, while for the blob you have to use
fabricCanvas.toCanvasElement(...) then move from canvasElement to blob if for any reason you prefer the blob advantages over dataUrls.
Related
I'm trying to create a web service in PHP that can deliver an SVG with reference to a PNG raster image. Both the data for the SVG as well as the binary PNG image come from a MySQL database on the server.
Option A: Encode the PNG data in base-64 and embed it directly in the SVG, such as:
<image xlink:href="data:image/png;base64,..."/>
Concerns: 30% heavier load than loading it as pure binary and noticeable delay when loading it with Postman (or is this just because of Postman).
Option B: Call the PNG data as binary and save it as a file on the file system, then call the SVG file, which would then reference the physical PNG file.
Concerns: Involvement of the file system (which implies I need to start managing physical files, expiration dates etc).
Is there perhaps another way that an SVG can reference the binary data on the fly without it having to be on the file system?
To accomplish something similar (in my case sending data for SVGs with additional data about each file as binary files, which are much smaller than sending xml, text, or json) - I use CBOR. In my case, I compress the SVG using LZString compression first, and add this along with additional data attributes to a JSON object. Then I convert the JSON object to CBOR. I think CBOR can handle your base 64 data without any need for conversion - more information about it is here: cbor.io
I found a PHP library for CBOR here: https://github.com/2tvenom/CBOREncode
This may not be the way to go at all for you, but I thought I'd throw it out there just in case.
I have several PNG images, which I need to combine as individual layers in a new GIMP XCF image. I need to perform this task many times, so a script based solution would be best.
So far i tried to play around with the batch mode of GIMP, but failed miserably.
Instead of script-fu, which uses Scheme, I'd recommend using the GIMP-Python binding for this, since it is far easier to manipulate files and listings.
If you check filters->Python->Console you will b dropped into an interactive mode - at the bottom of it, there will be a "Browse" button which lets you select any of GIMP's procedures in its API and paste it directly in this console.
There is as an API call to "load a file as a layer" - pdb.gimp_file_load_layer -
this however, brings the image to memory, but do not add it to the image - you have to call
pdb.gimp_image_insert_layer afterwards
You can type this directly in the interactive console, or,check one of my other GIMP-related answers, or some resource on GIMP-Python on the web to convert it to a plug-in, which won't require pasting this code each time you want to perform the task:
def open_images_as_layers(img, image_file_list):
for image_name in image_file_list:
layer = pdb.gimp_file_load_layer(image_name)
pdb.gimp_image_insert_layer(img, layer, None, 0)
img = gimp.image_list()[0]
image_list = "temp1.png temp2.png temp3.png"
open_images_as_layers(img, image_list.split())
The second to last line img = ... picks a needed reference to an open image
in GIMP - you could also create a new image using pdb calls if you'd prefer
(example bellow).
The file list is a hardcoded space separated string in the snippet above,
but you can create the file list in any of the ways allowed by Python.
For example, to get all the ".png" file names in a
c:\Documents and Settings\My user\Pictures folder, you could do:
from glob import glob
image_list = glob("c:/Documents and Settings/My user/Pictures/*png")
To create an image programatically:
img = gimp.Image(1024, 768)
pdb.gimp_display_new(img)
I am wanting to display the album artwork of a song (accessed via the taglib-sharp library) within a Windows Forms picture box. The problem I'm running into is that the taglib-library returns an image of type TagLib.IPicture whereas the picture box requires an object of type System.Drawing.Image.
I have scoured the internet for many hours now, looking for a way to convert from an IPicture to Image, but to no avail. The best lead I have is this: http://msdn.microsoft.com/en-us/library/system.windows.forms.axhost.getpicturefromipicture.aspx, but I have yet to see a successful example of how to implement this.
Any help as to how to convert between these two types would be much appreciated. Note: IPicture is not analogous to IPictureDisp in this case.
I've done the opposite before - turning an existing .jpg into an IPicture for embedding in an .mp3 file. I just tried reversing that operation and, after tweaking and testing, came up with this:
TagLib.File tagFile = TagLib.File.Create(mp3FilePath);
MemoryStream ms = new MemoryStream(tagFile.Tag.Pictures[0].Data.Data);
System.Drawing.Image image = System.Drawing.Image.FromStream(ms);
Thanks for the question - I already know how I'm going to use this myself!
Update: Here's the other way (.jpg to IPicture that I've done before):
tagFile.Tag.Pictures = new TagLib.IPicture[]
{
new TagLib.Picture(new TagLib.ByteVector((byte[])new System.Drawing.ImageConverter().ConvertTo(System.Drawing.Image.FromFile(jpgFilePath), typeof(byte[]))))
};
I have a code that handles displaying a blob from a local Oracle database. I store both JPG and PDF files as blob. I could view the JPG file, but not the PDF. I have checked these
$self->content_type('image/jpg')
to
$self->content_type('application/pdf').
And the Blob does have data. I checked the length and it has "184546".
All I get when I click the link for the pdf file is a blank page with the title GETIMAGPAGE(application/pdf).
Any help or pointers would be greatly appreciated.
Also, How can we have the content_type to enable two different mime_types? For example in my case both image as well as pdf, depending on what we get?
File::MMagic can recognize the type of data using magic numbers.
use File::MMagic;
$magic = File::MMagic->new;
$self->content($blob);
$self->content_type($magic->checktype_contents($blob));
If you don't want to require a native/plugin PDF reader, perhaps FlexPaper might fit your needs.
I want to retrieve the text from a pdf file using iTextSharp. However, I wasn't able to use PDFTextExtractor as in JAVA library of itextsharp(itext). I need readPDFOffline class to return content of file. I will give the pseudo below for you to understand well what I want.
private string readPDFOffline(string fileUri);
read PDF;
retrieve Text Content of This Pdf;*
save content into string contentOfflineFile;
return contentOfflineFile;
I would like to do the * part of Code
PdfTextExtractor is present in the most recent releases of iTextSharp, available here.
Retrieving text in PDF is not easy. Not impossible, but there are times when the only thing that will work is OCR. For all other cases, PdfTextExtractor should work. Cases of it not working are considered bugs and should be reported as such.
Be aware that there are several cases where what looks like valid text is not extractable:
Text with no encoding... just glyph indexes. OCR time.
"Text" that is just raw paths. Horribly inefficient, and time for more OCR.
"Text" that is pixels in a bitmap. OCR once more.
OCR: Optical Character Recognition. There's even a reasonably good one for free available on Google Code, though I don't recall the name off the top of my head.